1. Field of the Invention
The present invention relates to a three-dimensional pattern reflectors or reflective optical sensors for object attitude recognition.
The three-dimensional reflector embodied in the invention is such that its response to being illuminated by a source of radiation contains the necessary information for extracting the following parameters:
position of the reflector in a field of observation; PA1 distance from the reflector to the illuminating and detecting station; PA1 angular deviations between the reflector reference frame and the station reference frame; PA1 x.sub.E, y.sub.E, z.sub.E be the transmitter E coordinates; PA1 x.sub.D, y.sub.D, z.sub.D be the detector D coordinates; PA1 x, y, z be the coordinates of the running point P of the reflector; and PA1 N(x, y, z)=0 be the equation of the reflector in the x, y, z reference frame with the origin at O, the center of the reflector reference frame. PA1 x.sub.E =x.sub.D =x.sub.I ; x.sub.I =(x.sub.E +x.sub.D)/2 PA1 y.sub.E =y.sub.D =y.sub.I ; Y.sub.I =(y.sub.E +y.sub.D)/2 PA1 z.sub.E =z.sub.D =z.sub.I ; z.sub.I =(z.sub.E +z.sub.D)/2
The reflector response is quite distinct with respect to the background noise, thereby permitting identification thereof.
The response of the reflector embodying the invention to illumination is an array of discreet points the projections of which onto a plane are arranged in a curve that depends on the geometric structure of the reflector and the position thereof with respect to the radiating source.
The reflector embodying the invention are formed of a reflective surface that is spatially or locally periodic, carrying substantially parallel undulations and describing a certain geometric shape. When such a reflector is illuminated by a scanning beam or by an overall illuminating beam emitted by a transmitter, the beam, when it falls onto those points on the reflector where it coincides with the normal to the reflector surface, is reflected towards the transmitter where it is received by a detector arranged adjacently thereto and forming an imager therewith. The geometric location of the reflector points seen by the imager is the location of those points where the normals to said reflector run towards the imager.
Whenever the transmitter and detector are not adjacent, the location of the points the detector sees corresponds to that of the points where the normal to the reflector coincides with the line bisecting the angle formed by the directions joining the said points to the transmitter and to the detector.
The present invention also relates to a system for determining the position and the attitude of objects and, more particularly, a system of the kind in question that makes use of three-dimensional reflectors for object attitude recognition.
2. Description of the Prior Art
French Pat. No. 1,570,810 filed June 10, 1968 disclosed a corrugated reflector having concentric circular undulations. This reflector acts as a driving mirror for motor-cars and converts the image of a traffic light into a plurality of luminous points rectilinearly aligned. The point where the perpendicular from the traffic light falls onto the mirror is indeterminated and the mirror cannot serve to recognize the attitude of objects.